Shaft extension and coupling therefor



Dec. 19, 1939. R. E. SMITH SHAFT EXTENSION AND COUPLING THEREFOR Filed May 2'7, 1938 FIG) FIG. 2..

FIG. 3.

FIG.6.

FIG. 4.-. FIG. 5.

FIG. 7.

INVENTOR RAYMOND E. SMITH QQWUMKLL ATTORNEY Patented Dec. 19, 1939 PATENT OFFHCE SHAFT EXTENSION AND COUPLING THEREFOR Raymond E. Smith, Milwaukee, Wis., assignor to Globe-Union Inc., Milwaukee, Wis., a corporation of Delaware Application May 27, 1938, Serial No. 210,317

3 Claims.

This invention relates to an improvement in extension shafts and couplings therefor especially designed and adapted for use in connection with radio control devices such as volume controls, switches and the like.

One of the principal objects of the invention is to provide an extension shaft and coupling which greatly facilitates replacement or installation of control devices in a radio receiver and yet provides a strong, secure and steady assembly insuring convenient, reliable and uniform operation of the device with which it is associated. Another object of the invention is to provide a device of this character which is of simple, compact and closely organized construction, which is conveniently adaptable to a variety of installations, which is readily and easily assembled and disassembled and which may be economically manufactured from materials and by 20 means of facilities ordinarily available.

Other objects and advantages reside in certain novel features of the construction, arrangement and combination of parts which will be hereinafter more fully described and particu- 26 larly pointed out in the appended claims, reference being had to the accompanying drawing forming a part of this specification, and in which:

Figure 1 is a fragmentary View partly in side elevation and partly in longitudinal vertical sec- 30 tion showing one embodiment of the present invention;

Figure 2 is a fragmentary view in longitudinal section taken on line 22 of Figure 1;

Figure 3 is a view in transverse vertical cross 36 section taken on line 3-3 of Figure 1;

Figure 4 is a fragmentary view in elevation showing the slotted and grooved end of one of the shafts;

Figure 5 is a similar view showing the flat- 40 ened and notched end of the other of said shafts;

Figure 6 is a detail perspective view of the split retaining ring shown in Figures 1 to 3 for holding the shafts against axial movement with respect to each other; and

5 Figure 7 is a view in cross section similar to Figure 3 but showing a hairpin type of spring fastener employed in lieu of the split retaining ring.

Referring to the drawing, the numeral l0 des- 50 ignates a metal shaft of circular cross section and supported for rotation in a bushing H. The bushing H extends through an opening l2 in an insulating panel or support l3. A flange It integral with one end of the bushing engages one 55' side of the panel l3 around the margin of its of the bushing H to prevent axial motion of the 10"- shaft It in one direction. Usually similar means (not shown) is also provided to prevent axial motion of the shaft It] in the other direction also.

One end of the shaft It is provided with a transverse groove is], preferably extending di- 16' ametrically of the shaft and of rectangular shape. The slotted end of the shaft also has circumferentially extending grooves 20 intersecting the slot l9.

A cooperable shaft 2! is provided and in the 20 construction shown is constituted of fiat stock. It is not essential that the shaft 2| be of flat stock throughout its extent as the body of the shaft may take various shapes and cross sections. It is necessary however that the end of the shaft 2! adjacent the shaft Ill be flattened or equivalently shaped to adapt it to be interfitted snugly or frictionally with the slot IQ of shaft ID. The interfitting engagement between the shafts 2| and H! is such as to transmit torque and preclude relative angular movement. The end portion of the shaft 2| received in slot I9 is provided with peripherial notches 22 which register with grooves 20 in the assembly. A fastening device is fitted or received in the registering grooves and notches to hold the shafts I0 and 2! against relative axial motion. In the form of the invention shown in Figures 1 to 3 and 6, the fastening device takes the form of a resilient retaining ring 23 which is clinched into the grooves 20 and notches 22 in the manner illustrated in Figures 1 to 3 until the inner periphery of the ring lies well within said groove 20 and thereby positively holds the shaft 2| against axial displacement relative to the shaft 15 II]. In the form of the invention illustrated in Figure '7 this fastening or retaining device takes the form of a hairpin spring 25 which is snapped into the grooves 2|] and notches 22 and exerts a similar action. If desired the ring 23 or the spring 24 shown in Figs. 3 and 7, respectively, may be fitted within the groove 20 before the shaft sections are assembled and with this in mind the shaft section 2| may haveits end portion beveled or rounded as at 25 to provide opposed terminal camming portions which, as the shaft sections are engaged, will abut against the inner periphery of the ring 23 or spring 24 to expand the same, whereby to permit telescopic engagement of the shaft sections to an extent such as to bring the notches 22 in registry with the groove 20, at which time the ring or spring member will snap into the notches and effectively lock the shaft sections against separation.

In the construction illustrated, the shaft IE! is usually the driving shaft and the shaft 2| the driven shaft, although, of course, this relation may be reversed. Where the shaft I0 is the driving shaft it is equipped as a rule with an operating knob or a similar device and the shaft 2| is used to actuate a switch, such as a wave band switch or volume control or any other similar control device employed on radio receivers. This construction greatly facilitates replacement or even factory installation of control devices in radio receivers. The shafts 2i and It] may be provided in suitable lengths or may be cut to length, and yet in the assembly, a strong and secure, as well as a steady operation or actuation, is insured.

While I have shown and described several constructions in which the invention may be advantageously embodied, it is to be understood that the constructions shown have been selected merely for the purpose of illustration or example and that various changes in the size, shape and arrangement of the parts may be made without departing from the spirit of the invention or the scope of the subjoined claims.

The invention claimed is:

1. A control shaft coupling for adjustable electrical devices comprising a pair of shaft sections having interlocking portions for connecting them together end to end, said portions comprising non-circular interfitting parts fitting together to form a substantially circular joint, said interfitting parts being correspondingly grooved to provide a circumferential groove in said joint, a resilient split ring in said groove locking said sections together, the inner periphery of said ring lying completely within the groove.

2. A control shaft coupling for adjustable electrical devices comprising a pair of shaft sections of substantially the same diameter having interlocking portions for connecting them together end-to-end, one of said portions havin a slot extending back from its end and having a groove extending around said slotted region, the other of said portions comprising a tongue fitting into said slot, said tongue having edge notches in register with said groove when said shafts are in interlocked relation, and a resilient split ring in said registering groove and notches locking said shafts together, the inner periphery of said ring lying completely within said groove.

3. A control shaft coupling for adjustable electrical devices comprising a pair of shaft sections of substantially the same diameter having interlocking portions for connecting them together end-to-end, one of said portions having a slot extending back from its end and having a groove extending around said slotted region,

a resilient split ring seated in said groove, the other of said portions comprising a tongue fitting into said slot, said tongue having terminal cam portions engageable with the inner periphery of said ring through said slot to expand the ring as the tongue is fitted into said slot, said tongue also having edge notches in register with said groove and receiving said ring when said shafts are in interlocked relation, whereby to lock the shaft sections together.

RAYMOND E. SMITH. 

